As recited in JP 2013-31658A, conventionally known as a superconducting magnet device is a device provided with a magnet assembly including a superconducting coil, and a vacuum container which houses the magnet assembly.
The magnet assembly includes the superconducting coil, a refrigerant container which houses the superconducting coil together with a refrigerant such as liquid helium, and a heat-shield which covers the entire refrigerant container to shield heat radiation from the outside to the refrigerant container.
The magnet assembly should be supported while being suspended in the air within the vacuum container without contact with the vacuum container in order to suppress intrusion of heat from the vacuum container into the magnet assembly. The magnet assembly, however, includes the superconducting coil and the refrigerant container and is accordingly very heavy. Therefore, it is necessary to conceive a supporting structure of a magnet assembly, the structure being capable of simultaneously realizing reception of a heavy weight and suppression of intrusion of heat from the vacuum container to the magnet assembly.
For example, a possible supporting structure is a combination of a supporting member with high strength which is fixed to a vacuum container and is made of stainless or the like with flexural rigidity that allows reception of heavy weight of a magnet assembly, and a connecting member with low thermal conductivity which connects the supporting member and the magnet assembly.
However, since the supporting member receiving heavy weight requires a size for ensuring rigidity, down-sizing of the supporting member is difficult. Accordingly, for housing such a supporting member as receiving a heavy weight within a vacuum container without interference with a magnet assembly, an internal space of the vacuum container is inevitably increased. This resultantly makes it difficult to reduce the vacuum container in size.